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Recombination Frequency Calculator

Calculate recombination frequency from offspring counts.

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Recombination Frequency

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Overview

Recombination frequency measures the proportion of offspring that express a combination of alleles different from their parents due to crossing over during meiosis. This value is used to determine the genetic distance between two loci on a chromosome, where 1% recombination equals 1 centimorgan.

Symbols

Variables

% = Recombination Frequency, R = Recombinant Offspring, T = Total Offspring

%
Recombination Frequency
Variable
Recombinant Offspring
Variable
Total Offspring
Variable

Apply it well

When To Use

When to use: Apply this formula when analyzing the results of a testcross involving two or more linked genes. It is most accurate when the genes are relatively close together, as double crossovers can underestimate the distance between distant genes.

Why it matters: Calculating these frequencies allows scientists to build genetic maps that show the physical arrangement of genes on chromosomes. This is vital for identifying genes associated with hereditary diseases and improving crop yields in agriculture.

Avoid these traps

Common Mistakes

  • Using total offspring instead of recombinants.
  • Forgetting to multiply by 100.

One free problem

Practice Problem

In a genetic cross involving fruit flies, a researcher counts 1,000 total offspring. If 140 of these offspring exhibit recombinant phenotypes for eye color and wing length, what is the recombination frequency?

Recombinant Offspring140
Total Offspring1000

Solve for: RF

Hint: Divide the number of recombinants by the total number of offspring and multiply by 100.

The full worked solution stays in the interactive walkthrough.

References

Sources

  1. Campbell Biology
  2. Wikipedia: Recombination frequency
  3. Griffiths, A. J. F., Wessler, S. R., Carroll, S. B., & Doebley, J. (2015). An Introduction to Genetic Analysis (11th ed.). W. H.
  4. Wikipedia: Centimorgan
  5. Griffiths, Anthony J.F., et al. An Introduction to Genetic Analysis. W. H. Freeman and Company.
  6. Pierce, Benjamin A. Genetics: A Conceptual Approach. W. H. Freeman and Company.
  7. IUPAC Gold Book: recombination frequency
  8. AQA A-Level Biology — Genetics